effect of fiber orientation on mechanical properties of
TRANSCRIPT
Effect of Fiber Orientation on Mechanical Properties
of Sisal Fiber Reinforced Epoxy Composites
Kumaresan. M1*, Sathish. S2 and Karthi. N3
1Kalaignarkarunanidhi Institute of Technology, Coimbatore-641402, Indian2KPR Institute of Engineering and Technology, Coimbatore-641407, Indian
3Sri Krishna College of Technology, Coimbatore-641042, Indian
Abstract
This present work evaluated the effect of fiber orientation on mechanical properties of sisal
fiber reinforced epoxy composites. In this work sisal fiber is used as reinforcement which treated with
NaOH solution for enhancing the bonding strength between fiber and resin by removing moisture
contents. Samples of different orientations of sisal fiber reinforced composites were fabricated by
compression molding and investigated their mechanical properties like tensile strength and flexural
strength. The work of this experimental study has been carried out to determine the mechanical
properties due to the effect of sisal fiber orientations such as 0�/90�, 90�and �45� orientation. The
results of this study indicate the orientation 90� shows the better mechanical properties compare than
0�/90� and �45�.
Key Words: Sisal Fiber, Epoxy Resin, Compression Molding, Fiber Orientation
1. Introduction
Fiber reinforced polymer composites are being used
in almost every type of applications in our daily life and
its usage continues to grow at an impressive rate. The
manufacture, use and removal of traditional composite
structures usually made of synthetic fibers are consi-
dered critically because of the growing environmental
pollution. It creates interest in the use of biofibers as re-
inforcing components for thermoplastics and thermo sets.
Sisal fiber (SF), a member of the Agavaceae family is a
biodegradable and environmental friendly plant. Sisal fi-
ber is a strong, durable, stable and versatile material and
it has been recognized as an important source of fiber
for composites. It is generally accepted that the mechani-
cal properties of fiber reinforced polymer composites are
controlled by factors such as nature of matrix, fiber-ma-
trix interface, fiber volume or weight fraction, fiber as-
pect ratio, fiber orientation etc [1]. The combination
results in superior properties not exhibited by the indi-
vidual materials. Many composite materials are com-
posed of just two phases one is termed as matrix phase,
which is continuous and surrounds the other phase often
called the dispersed phase [2�5]. Composites reinforced
with natural fibers received increasing interest from in-
dustries in a wide field of application such as automo-
bile, construction, aerospace and packing (Ku H et al.
2011; Pickering KL et al. 2007). The main drawback of
using natural fiber is their high level of moisture ab-
sorption, insufficient adhesion between untreated fibers
and the polymer matrix which can lead to deboning with
age (Gassan J 2002). Many of the plant fibers such as
coir, sisal, jute, banana, palmyra, pineapple, talipot, hemp,
etc. find applications as a resource for industrial mate-
rials (Satyanarayana et al., 1990b; Thomas & Udo, 1997;
Rowell et al., 1997) Proper design of a composite system
subjected to high loading rates can be accomplished only
if the strain rate sensitivity of the material has been mea-
sured and the modes of failure and energy absorption are
well characterized [6]. For instance, sisal is a hard leaf
fiber but jute and hemp are both bast fibres and are gen-
erally referred to as ‘soft’ fibers to distinguish them from
Journal of Applied Science and Engineering, Vol. 18, No. 3, pp. 289�294 (2015) DOI: 10.6180/jase.2015.18.3.09
*Corresponding author. E-mail: [email protected]
the hard leaf fibers. Both leaf and bast fibres are multi-
cellular with very small individual cells bonded to-
gether (Preston, 1963; Hearle, 1963 and Hegbom, 1990).
Composites filled with micro particles in epoxy system
gained significant importance in the development of
thermosetting composites. Epoxy resins the most im-
portant matrix polymer preferred when it comes to high
performance. Its combination with glass fibers gives an
advanced composite with properties like low weight,
good mechanical and tribological properties [7�16]. The
study deals with the effects of natural fibers on some
mechanical properties of the Epoxy composite. Jayamol
George [17] made experimental studies on Short Pine-
apple-Leaf-Fiber-Reinforced Low-Density Polyethylene
Composites. The influence of fiber length, fiber loading,
and orientation on the mechanical properties has also
been evaluated. Measurement of fiber length is often
performed on photographs of short fibers obtained from
burning off or dissolving the matrix. Correction of the
measurement of fiber length was carried out and the real
value of mean fiber length and the real fiber length distri-
bution were obtained [18].
2. Materials and Methods
2.1 Sisal Fiber
Sisal is a natural fiber (Scientific name is Agave si-
salana) of Agavaceae (Agave) family yields a stiff fiber
traditionally used in making twine and rope. Sisal is fully
biodegradable and highly renewable resource of energy.
Sisal fiber is exceptionally durable and a low mainte-
nance with minimal wear and tear strength. Sisal fiber is
produced by the way known as decortications, where
leaves are compressed by a rotating wheel set with blunt
knives, so that only fibers will remain.
2.2 Physical Property Sisal Fiber
Density (g/cm3) upto1.5
Specific modulus (Gpa) 6�15
Cellulose content (%) 67�78
Young’s modulus (Gpa) 9�22
Diameter of ultimates (�m) 18.3�23.7
2.3 Matrix and Hardener
Epoxy is a thermosetting polymer that cures when
mixed with a hardener. Epoxy resin of the grade LY556
was used in this study. The hardener of the grade HY-
951. The reinforced matrix material was prepared with a
mixture of epoxy and hardener at a ratio of 10:1.
2.4 Chemical Treatment
Alkali treatment or mercerization using sodium hy-
droxide (NaOH) is the most commonly used treatment
for bleaching and cleaning the surface of natural fibers
to produce high-quality fibers. 5% NaOH solution was
prepared using sodium hydroxide pellets and distilled
water. When the percentage of NaOH is increased it af-
fect the fibers properties by reduce the bonding capacity
during preparation of composites. Sisal fibers were then
dipped in the solution for 2 hour separately. Then it is
washed with running water. It was then kept in hot air
oven for 3 hours at 80 �C.
2.5 Composite Preparation
Mold is used for preparing the specimen which is
made up of EN90 steel and having dimensions of 250
� 250 � 5 mm. First, the mould is polished and then a
mould releasing agent is applied on the surface used to
facilitate easy removal of the composite from the mold.
The epoxy resin LY556 and hardener (HY951) is mixed
in a ratio of 10:1 by weight as used. The weight per-
centage of fiber used is 250 grams. The sisal fiber are
placed over the mold at required orientation manually
and then required amount of epoxy resin was poured
over it. The process is continued until the required thick-
ness and weight percentage of fiber was obtained. For
each time a roller was used to roll over the fiber in order
to remove the air bubbles from it. It can pressed in a hy-
draulic press at the temperature of 120 �C for 30 minutes
and a pressure of 35 kg/cm2 for 45 minutes is applied be-
fore it is removed from the mould. After this sample is
post cured at atmosphere for three hours of time accord-
ing to the manufacturer’s guidance. Figure 1 shows the
compression molding machine with specimen.
3. Experimental Tests
3.1 Tensile Test
The tensile test specimen is prepared according to
the ASTM D3039 standard and the machine specifica-
290 Kumaresan. M et al.
tions are also chosen according to the ASTM D3039. Ac-
cording to the ASTM D3039 standard the dimensions of
specimen used are 250 � 25 mm. This test involves plac-
ing the specimen in a machine and subjecting it to the
tension according to specific load until it fractures. Fig-
ure 2 shows the tensile testing machine with specimen.
3.2 Flexural Test
Flexural test is also known as bending test and con-
sists in applying a point load at the centre of composite
material specimen. The flexural tests were done on the
universal testing machine according to ASTMD790 with
the crosshead speed of 10 mm/min. According to the
ASTMD790 standard the dimensions of specimen used
are 125 � 12.7 mm. Figure 3 shows the flexural testing
machine with specimen.
3.3 Impact Test
Impact test were carried out using charpy impact test
machine with specimen is shown in Figure 4 with stan-
dard of ASTM A370. Generally sisal fibers possess good
impact absorbing properties. The fracture values were
calculated by dividing the energy by cross sectional area
of the specimen.
4. Results and Discussion
The test results are shown and discussed in this sec-
Effect of Fiber Orientation on Mechanical Properties of Sisal Fiber Reinforced Epoxy Composites 291
Figure 2. Tensile testing machine.
Figure 3. Flexural testing machines.
Figure 4. Impact testing machine.
Figure 1. Compression molding.
tion. Table 1 shows the tensile test results for different
orientations of treated sisal fiber reinforced composites
are listed and compare them. In this we take 3 trials of
specimens for testing tensile strength. Among these the
orientation 90� (uni directional) shows maximum strength.
Figure 5 shows the tensile strength of treated sisal
fiber reinforced composites on their different orienta-
tion. Among these the orientation 90� orientation (uni
directional) shows maximum tensile strength.
Table 2 shows the flexural test results for different
orientations of treated sisal fiber reinforced composites.
In this we take 3 trials of specimens for testing tensile
strength. Among these the 90� orientation (uni direc-
tional) shows maximum flexural strength.
Figure 6 shows the flexural strength of treated sisal
fiber reinforced composites on their different orientation.
Among these the 90� orientation (uni directional) shows
maximum flexural strength.
Table 3 shows the impact test results for different
orientations of treated sisal fiber reinforced composites.
The 90� orientation (uni directional) shows the maxi-
mum impact strength of 7.30 joules obtained.
Figure 7 shows the impact strength of treated sisal
292 Kumaresan. M et al.
Table 1. Tensile testing result
Specimen
orientation
No. of
trials
Ultimate
tensile
load (N)
Tensile
strength
(MPa)
Elongation
at break
(%)
T1 2048.22 16.28 2.36
T2 2123.43 16.87 2.43
T3 2110.16 17.07 2.110�/90�
Avg 2093.93 16.74 2.30
T1 4820.27 38.22 4.12
T2 4894.44 37.91 4.44
T3 4854.46 40.36 4.2490�
Avg 4856.39 38.83 4.26
T1 2496.68 19.76 2.81
T2 2464.32 19.21 2.88
T3 2493.52 20.64 2.50�45�
Avg 2484.82 19.87 2.73
Figure 5. Tensile strength results.
Table 2. Flexural test results
Specimen
orientation
No. of
trials
Flexural load
(N)
Flexural strength
(MPa)
T1 282.16 88.56
T2 282.75 94.50
T3 284.52 91.280�/90�
Avg 283.12 91.44
T1 467.19 175.36
T2 470.26 187.52
T3 467.21 97.7790�
Avg 468.22 151.12
T1 199.21 68.36
T2 202.54 76.12
T3 202.26 50.59�45�
Avg 201.34 65.02
Figure 6. Flexural strength results.
Table 3. Impact test results
Orientations 0�/90� 90� �45�
Impact strength (joules) 3.65 7.30 5.75
Figure 7. Impact strength results.
fiber reinforced composites on their different orienta-
tion. Among these the 90� orientation (uni directional)
shows maximum impact strength.
5. Conclusions
In the present work three types of orientations were
achieved as per ASTM standards were used for testing.
The part might require 0� to react to axial loads, �45�
to react to shear loads, and 90� to react to side loads.
The experimental investigation on the effect of fiber ori-
entation on the treated sisal fiber reinforced epoxy com-
posites leads to following conclusion. The mechanical
properties such as tensile strength and flexural strength
shows the maximum value of 38.84 Mpa and 151.22
Mpa in the 90� orientation (uni directional) compared to
others. Generally sisal fibers possess good impact ab-
sorbing properties. The charpy impact strength of treated
sisal fiber reinforced composites show the orientation 90�
(uni directional) yielded the maximum impact strength
of 3.53 J.
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